Endoscopic surgery and diagnosis are considerably less invasive than the conventional procedures. This results in a lower mortality rate and minimizes both the patient's hospital stay and recovery time.
Conventional endoscopes include a rigid elongated member, a lens assembly, and an imaging device mounted either on or within the endoscope. Examples of such endoscopes are described in U.S. Pat. Nos. 4,697,210 (Toyota et al.), 4,791,479 (Ogiu et al.), and 4,989,586 (Furukawa).
Although a conventional endoscope can be constructed to have a wide field of view, the picture quality suffers. As a practical matter, the field of view of conventional endoscopes must be relatively narrow. As a result, a conventional endoscope must be positioned carefully at the beginning of a procedure, then held in position throughout the procedure, which generally requires the full-time attention of one member of the operating team. U.S. Pat. No. 5,351,678 (Clayton et al.) addresses the initial positioning problem by providing an endoscope having a distal end which is offset from the endoscope's longitudinal axis. With the Clayton et al. endoscope, the surgeon can easily change the area viewed by rotating the endoscope about its longitudinal axis. However, the Clayton et al. endoscope must still be held in place throughout the procedure by a member of the operating team.